Start-stop mechanism



Sept. 27, 1932.

R. D. SALMON 1,879,525

START-STOP MECHANISM Filed July 28, 1951 INVENTOR REGINALD D. SALMON ATTORNEY Patented Sept. 27, 1932 UNITED STATES PATENT OFFICE REGINALD DENNIS SALMON, OF CROYDON', ENGLAND, ASSIGNOR TO CBEED AND COM- PANY, LIMITED, 0F CROYDON', ENGLAND START-STOP MECHANISM Application filed July 28,1931, Serial No. 553,577, and in Great Britain May 14, 1931.-

This invention relates to an improved startstop clutch mechanism and is particularly suitable for telegraph apparatus.

In clutch mechanism adapted to rotate for a one revolution only at each operation, it is necessary to provide means operable during the rotation of the clutch member to effect the return of a controlling detent to a position to re-arrest the clutch member.

In a one revolution clutch mechanism adapted to operate telegraphic and like signalling apparatus, it is very desirable that the clutch mechanism be robust and capable of effecting the operation of its associated apparatus and yet that the force required to effect the release of the clutch be as small as possible.

In a one-revolution clutch mechanism for a printing telegraph receiving apparatus,

sive to successive elements of received signals effects the release of a clutch on receipt of the first element of aseries of impulses, and thereafter effects the actuation of a selecting mechanism in accordance with the character of each of a series of succeeding permutation impulses, it is very desirable that after the release of the clutch, the relay or magnet be relieved of as much load as possible, incurred in eifecting this release of the clutch, during the subsequent actuation of the selecting mechanism.

These conditions are satisfied by the form of construction according to the present invention by which a one-revolution clutch mechanism comprises a detent controlling a rotatable clutch member which is operable by the action of spring means and under the control of latch means, to a position to release the clutch member for rotation, which member during subsequent rotation effects the return of the detent to a position to re-arrest the clutch member.

When the arrangement is particularly adapted to operate under the control of a relay or magnet in a start stop telegraph receiv ing apparatus as hereinbefore mentioned, the relay or magnet is arranged to control the latch means for releasing the detent and during the subsequent rotation of the clutch moreover in which a relay or magnet responmember the return of the detent is effected to a position beyond the resetting position of these latch means whereby in addition to ensuring one revolution only of the clutch member at each release, the latch means are held out of operative relation with the controlling means during the period in which the receiving relay is responding to the series of permutation impulses.

A feature of importance in start-stop receiving apparatus of the type herein mentioned is that known as orientation and consists in arranging for the selecting periods of the cams actuated through the clutch member, to occur as nearly as possible simultaneously with the strongest portion of each of the corresponding selecting impulses received over the line circuit. The time interval between the release of the clutch in response to the first Or starting impulse and the response of the receiving relay to the succeeding permutationa impulse varies slightly in accordance with the characteristics of the line circuit over which the signal impulses are transmitted and received. Means will be shown whereby orientation can be conveniently effectedwith the arrangementaccording to the present invention.

For a better comprehension of these and other features, the invention will be described in conjunction with the single figure of the accompanying drawing. 7

Referring to the drawing, a rotatable clutch member 1 carries a clutch pawl 2 and forms the driven member of any convenient type of clutch. A detent 3 pivoted at 4 to a fixed portion of the apparatus controls the rotation of the clutch member 1, by engaging or releasing pawl 2. A. spring 5 tends to actuate detent 3 to a position against stop 6 in which position pawl 2 and clutch member 1 are released for rotation.

Pivoted at the free end of detent 3 is a latch member 7 the other end of which latches with a fixed member 8. A spring 9 tends to maintain the latching members"? and 8 in engagement. Engaging with a projection 10 formed on latch member 7 is a controlling member 11 movable in a verticaldirection of motion to unl'atch members 7 and 8-. The

movement of the controlling member 11 may be efiected by any convenient means in accordance with the purpose to which the arrangement is to be adapted. In the drawing, controlling member 11 is shown pivoted on one arm of a roclrshaft 12 which in turn is actuated through another arm and a link 13 from the armature 22 pivoted at 23 of a relay or magnet 2425. Arranged or formed integrally with clutch member 1 is a cam surface 14 with which cooperates one arm 15 of a bell-crank lever pivoted at 16. The second arm 17 of the ell-crank lever carries a projection 18 which engages with detent 3. A notch or depression 19 is formed in cam surface 14 in such a position that a roller or other convenient cooperating portion of arm 15 enters therein and permits the other arm 17 with projection 18 of the bell-crank lever to move away from engagement with detent 3. At any other period of its revolution, cam surface 14 actuates the bell-crank lever and detent 3 against the tension of spring 5 to a position to re-arrest clutch member 1 through pawl 2.

The controlling member 11, as previously mentioned, engages with a projection 10 formed on latch member 7. For this purpose a notch is formed in controlling member 11 and a fixed stop member 20 is situated in a position to limit the depth of engagement of the notch in controlling member 11 with projection 10 when latch member 7 is latching in turn with fixed member 8. A light spring 21 tends to maintain controlling member 11 in sliding contact with its stop member 20 but permits a pivoting movement on the arm of roclrshaft 12. The cam surface 14, notch 19, arm 15, and projection 18 are so proportioned and arranged that upon rotation of clutch member 1, the bell-crank lever is actuated in a counter-clockwise direction and detent 3 is positively returned by means of projection 18 into a position to rearrest the clutch member 1'. This return movement of detent 3 under the action of cam surface 14, not only carries latch member 7 into a position to relatch with fixed member 8, but carries it further so as to withdraw projection 10 from operative relation with the notch in controlling member 11 as limited in the position of the latter by stop member 20. During the rotation of clutch member 1, therefore, the movement of the controlling member 11 is unimpeded by the clutch controlling means and on completion of one revolution, notch 19 permits projection 18 on the bell-crank lever to withdraw from detent 3 which is thereupon retracted by spring 5 until latch member 7 engages with stop member 8. In this position pawl 2 is still held by detent 3 but controlling member 11 can now 're-engage with projection 10 on latch member 7.

It will thus be seen that the whole arrangeis completed projection 10 will cause controlling member 11 to pivot slightly on the arm of the rockshaft 12, but another revolution will not ensue until the controlling member 11 has been raised to enable the notch therein to re-engage with projection 10.

It will be noted that a relatively strong spring 5 can be used to retract detent 3 and still only require a small force to trip latch members 7 and 8 as the detent is reset by the mechanical force transmitted through the clutch. All reaction on the controlling member due to drag of the clutch members is also eliminated. A robust construction is thereby achieved and yet only requiring light controlling forces.

When the controlling member is actuated by a relay or magnet responsive toreceived signal impulses in start stop telegraph receiving apparatus, for example, it is an advantage to separate the function of releasing a clutch in response to the first element of a series of impulses and thereafter effecting the actuation of a selecting mechanism in accordance with the character of each succeeding impulse. This is of particular importance when the apparatus is to be adapted for closed line circuit working but in which current is removed from the line circuit during idle periods. Under these conditions the normal position of the receiving relay during reception of signals will be with the clutch at rest and with current flowing in the line circuit and relay. "When current is removed fro-1n the line circuit upon cessation of signalling the relay falls to the opposite position which is then known as the false normal position. This releases the clutch of the receiving apparatus and with the automatic devices usually provided for stopping the motor the cam shaft then comes to rest in an indeterminate position. Upon restarting the motor on resumption of signalling the last revolution will be completed and probably an indeterminate character will be printed.

With the present arrangement, when the relay falls to the false normal position only one idle revolution of the clutch and cam shaft ensues, and is then arrested whilst the I above relative to actuatinglatch member 7 during rotation of clutch member 1 to a position where projection 10 is out of operative relation with controlling member 11 until the end of each revolution. In receiving apparatus of the class now under consideration, other means, not shown in the drawing, would be operated from rockshaft 12 to effect the actuation of a selecting mechanism after the release of the clutch member 1 and in accordance with the character of each of the series of succeeding permutation impulses. After the tripping of the clutch member controlling detent 3 the mechanical power controlled thereby withdraws the clutch controlling means from operative relation with rockshaft 12 during that period in which the movements of the rockshaft are utilized for effecting the actuation of the selecting mechanism. For controlling the clutch, therefore, the receiving relay is only required to unlatch members 7 and 8 through controlling member 11 and during the selecting operation of the receiving apparatus only the slight friction due to the movement of the controlling member 11 on stop member 20, and the inertia of the former member, impede the movements of the relay armature. Both of these factors can be made Very small.

The drawing also shows a convenient method in the arrangement according to the present invention whereby the time interval between the response of the relay to effect the release of the clutch and the operations affected b the selecting cams driven thereby can be adjusted to compensate for any variation in the characteristics of the line as previously mentioned, over which signals are being received. This method consists of providing adjusting means for varying the tension of spring 5 which actuates detent 3. As previously explained, this spring can be of relatively considerable strength as the receiving relay is merely required to trip the latch member 7 If the tension is reduced, by turning screw adjusting head 22 as shown for instance, the detent 3 will not be actuated so rapidly to a position to relase the clutch member 1 for rotation. In these circumstances, the periods of actuation by the selecting cams will be retarded relatively to the instant of response of the receiving re lay to the starting impulse, and if the spring tension is again increased the selecting cam periods will be advanced. Other means to vary the rapidity of response of detent 3 to the actuating movement of the relay armature will be evident to those skilled in the art. The arrangement according to the present invention provides a wide margin for adjustment without rendering the operation thereof uncertain.

It will be appreciated that whilst all of the features hereinbefore described are shown in the drawing as incorporated in a single arrangement, the invention is consid ered tolreside not merely in the combination of all these features.

The following claims represent those points which it is thought constitute the patentable features of the invention and it will be noted that within the scope of these claims considerable modifications can be effected tothe relative parts as compared with those of the arrangement herein shown by way of example.

' What is claimed is: r

1. A start-stop mechanism comprising a rotatablefriction clutch, a detent controlling the rotation of said clutch, spring means tending to. actuate said detent to a position to release said clutch member for rotation, cam means actuated by said clutch during rotation except at its release, means operated by said cam means to immediately return said detent positively to a position to arrest said clutch, and means controlling thefactuation ofrsaid detent under the influence of said spring means for releasing said clutch.

2. A start-stop mechanism comprising a rotatable clutch, a detent, spring means to actuate said detent to a position to release said clutch member for rotation, a latch memberpivoted at one end thereof to said 93 detent and latching with a fixed member at the other end, a controlling member operable in one direction of motion to unlatch said latch member and yieldably movable therewith in a second direction of motion, and means operable on commencement of rotation of said clutch member to immediately return said detent to a position to arrest the rotation and to reset said latch members.

3. In a telegraph receiving'apparatus, a clutch, a detent controlling said clutch, spring means to actuate said detent to a position to release said clutch, a relay responsive to successive elements of received signals, latch means operated thereby and controlling the release of said detent, and cam means operable upon commencement of rotation by said clutch to move said detent to a position to arrest said clutch in which position said latch means operated by said relay are out of operative engagement and on completion of a revolution of said cam means permit said latch means to re-engage in operative relation.

4:. In a telegraph receiving apparatus, a clutch, a detent controlling said clutch, spring means to actuate said detent to a position to release said clutch, a latch member pivoted at one end to said detent and at the other end latching against a fixed member, a relay or magnet responsive to successive elements of received signals, a controlling member actuated thereby and engaging with a projection on said latch member to unlatch the latter from said fixed member, and means operable on commencement of rotation of said clutch to operate said detent to and maintain it in a position to rearrest said clutch in which position said controlling member is out of operative relation with the projection on said latch member.

5. In a telegraph apparatus, a clutch, a de tent for controlling said clutch and operable into one of three positions, means to hold said detent latched in an intermediate position which holds said clutch against rotation, a relay or magnet responsive to successive elements of received signals, means actuated thereby to unlatch said detent to cause it to assume a position to release said clutch, and other means operable on commencement of rotation of said clutch to actuate said detent to a third position beyond the re-latching position and out of operative relation with said un-latching means in which position the clutch will be re-arrested upon completion of its rotation.

6. In a telegraph receiving apparatus the combination as set forth in claim 2 together with adjusting means for the spring means actuating said detent to a position to release the clutch.

7. A start-stop mechanism, comprising a rotatable clutch, a detent co-operating with a lug on said clutch for stopping the rotation of said clutch, a latch member having one end pivoted on said detent and the other end latched by a fixedmember, means for releasing said latch member, and means effective when said clutch begins to rotate for so positioning the detent that said clutch is arrested after one revolution.

8. In a start-stop mechanism, the combination as set forth in claim 7, together with ad'- justable spring means to actuate said detent to a position for releasing said clutch.

In witness whereof I hereunto subscribe my name this twenty-third day of June, 1931.

REGINALD DENNIS SALMON. 

